Major depressive disorder is associated with significant morbidity and mortality. According to the WHO, depression is the leading cause of disability worldwide in terms of years lost due to disability [1]. Although depressive symptoms are amenable to antidepressant treatment, a high proportion of patients does not respond or remit. For example in the Sequenced Treatment Alternatives for the Relief of Depression (STAR*D) study the response and remission rates with stage 1 treatment (citalopram) were 49% and 37% respectively and these rates decreased to 16% and 13% respectively over the subsequent next three treatment steps [2]. Clearly there is a need for new treatment approaches.